New ‘Biggest Loser’ Study Shows Why It’s So Hard to Keep Off Lost Weight

A new study explains the significant biological hurdles that make it so hard to keep off weight lost, the New York Times reports, citing the striking experiences of contestants on the reality TV show The Biggest Loser.

In the study, published Monday in the journal Obesity, scientist Kevin Hall and other researchers tracked 14 contestants from the eighth season of the show over a period of six years. The reality TV show challenges participants to lose as much weight as possible in a short time through intense diet and exercise regimens.

Not only did 13 out of the 14 former contestants regain weight by the end of that stretch—four of them actually weighed more than they did at the beginning of the competition in 2009. Season 8 winner Danny Cahill packed on more than 100 pounds after losing 239 pounds during the show.

Scientists explain that the body’s metabolism rebels against weight loss efforts, slowing down both during and after diet and exercise programs. But the Biggest Loser study underscores just how steep the drop in metabolism can be—and, in a worrying twist, how long it can persist.

To cite just one example, Cahill now burns a staggering 800 fewer calories per day while at rest than expected, meaning he needs to consume considerably less food just to maintain equilibrium. That may not be much of a surprise given his transition from a temporary, extreme lifestyle to a more normal routine.

But the fact that his and the other study subjects’ metabolism hasn’t been able to claw its way back to a more rapid clip suggests that tackling excess body weight and obesity may be even more difficult than originally imagined. And that could have far-reaching consequences for future public health in light of America’s obesity crisis.

Nearly 35% of U.S. adults are obese, costing $147 billion per year in medical spending, according to the CDC. The trend is being passed on to the next generation. In fact, just last week, another new study by researchers at the Duke Clinical Research Institute found that 33.4% of children aged 2-to-19 are overweight, and more than 17% of that group is obese.

That stands contrary to some other studies finding significant declines in the childhood obesity rate over the past decade.

“Despite some other recent reports, we found no indication of a decline in obesity prevalence in the United States in any group of children aged 2 through 19,” said lead study author Asheley Skinner, an associate professor at Duke. “This is particularly true with severe obesity, which remains high, especially among adolescents.”